Lichen sensitivity to air quality has been recognized in Europe
for over 125 years: recently Federal agencies in this country have
begun using lichens as air quality bioindicators. This study presents
the results of three different approaches to air quality biomonitoring
using lichens: (1) a lichen community analysis, (2) an elemental
analysis of lichen tissue content, and (3) the growth of removable
lichen transplants. The lichen community and elemental tissue content
analyses were part of an air quality baseline on the Tongass National
Forest in southeast Alaska. The lichen transplant experiment compared
the growth of three different lichen species and evaluated and refined
a transplant technique in western Oregon.
Lichen communities were sampled on 50 Pinus contorta peatlands
in southeast Alaska. These peatlands make good air quality
biomonitoring sites because: (1) the trees are slow growing and
provide stable substrates for lichen colonization; (2) many branches
are at eye level, making the canopy epiphytes easily observable; (3)
the scattered, open distribution of the trees allows for good air
circulation on the sites; and (4) precipitation, light conditions, and
relative humidity are high, which stimulate lichen growth.
A total of 100 lichen species were encountered during whole-plot
ocular surveys of each plot. Multivariate ordination revealed what
appears to be a successional gradient represented by high cover of
Bryoria species at older sites and high cover of Platismatia
norvegica, P. glauca, Hypogymnia enteromorpha sens. lat. and H.
inactiva at younger sites. A second pattern revealed by ordination
analysis appears to be a climatic gradient with high Alectoria
sarmentosa cover on moister, warmer sites, and high cover of Bryoria
species on drier, colder sites. The first two gradients contained 35%
and 21%, respectively, of the information in the analytical data set
(cumulative r��=56%).
Elemental tissue content of Alectoria sarmentosa was determined
from 43 of the peatland plots in southeast Alaska. The range of
values for 16 elements are reported and compared to other regional
studies; the ranges of values for most elements were within normal
background levels. Quality assurance techniques are described for
separation of laboratory and field noise from elemental content
signal. Principal components analysis was used to create three
synthetic gradients of plot-level elemental content. The first three
principal components captured 55% of the correlation structure among
elements. Iron (r=-0.91), aluminum (r=-0.80) and chromium (r=-0.71)
are all highly correlated with the first gradient. This gradient
could represent sites enriched by elements from dirt; aluminum and
iron silicates are both persistent and abundant components of
weathered rock and soil. Potassium (r=-0.82), phosphorous (r=-0.63),
zinc (r=-0.60), manganese (r=-0.58), magnesium (r=-0.51) and nickel
(r=0.54) are correlated with the second gradient. Many of these
elements are supplemented by salt water aerosols (Nieboer et al. 1978;
Rhoades 1988). Lead (r=0.70) and cadmium (r=0.59) were correlated
with the third axis. This gradients could represent enrichment from
fossil fuel combustion. Recommendations for standardizing future
regional studies of lichen elemental content are made.
Removable lichen transplants were constructed using live thalli
of known weight, a 5 cm length of nylon monofilament, silicone glue,
and reusable attachment mechanisms. Transplants were returned to
several sites in Western Oregon and were weighed every several months
for 13 months. Reference standards for each species were used to
correct for changes in lichen water content due to changes in lab
humidity. Despite apparent vigor, Alectoria proved unsuitable for
repeated weighings because of biomass loss due to fragmentation
(average of 9% biomass loss). Growth of Evernia and Lobaria
transplants differed both between species and between sites. Average
growth over the 13 months for Evernia in the foothills and valley was
40% and 30% respectively; for Lobaria it was 16% and 15%. Differences
in growth between species could be due to different: (1) growth rates;
(2) sensitivities to air quality; (3) sensitivities to microhabitat;
and (4) sensitivities to transplant trauma. Differences in growth
between valley and foothill sites could be due to differences in: (1)
micro- or macrohabitat conditions; and (2) air quality. / Graduation date: 1995
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/35262 |
| Date | 09 December 1994 |
| Creators | Derr, Chiska C. |
| Contributors | McCune, Bruce P. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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